SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '384bc3dc812b7cfb9205b63687bdfd9b1d57909e662f82b0650cd74a39e77f04' 
  AND token = 'hl+b6DY3CPVHhD4KkUkfyQ1bsMgAJ20fJrHsnHDDC8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}